1. Field of the Invention
This invention relates to the fluorination of carbanions with N-fluoro-N-alkylsulfonamides.
2. Background Information
N-Fluoro-N-alkylsulfonamides are known and their preparation by reaction of N-alkylsulfonamides with fluorine/inert-carrier-gas mixtures is disclosed in general terms in the art.
Barton et al., JCS Perkin Trans., 1, 732 (1974); U.S. Pat. No. 3,917,688 and DE No. 2,332,430 all disclose processes for the preparation of N-fluoro-N-alkylsulfonamides by the reaction of sulfonamides with trifluoromethyl hypofluorite, according to the equation: ##STR3## wherein R.sup.1 and R.sup.2 are hydrocarbyl groups or substituted hydrocarbyl groups. U.S. Pat. No. 3,917,688 further discloses that fluorine may be used in the preparation of N-fluoro-N-alkylsulfonamides, but that carefully controlled reaction conditions will generally be necessary to minimize the extent of unwanted side reactions. The fluorosulfonamides so obtained were further converted to biologically active fluoroamines.
Seguin et al., J. Fluorine Chem., 15, 201 (1980) disclose the preparation of N-fluoro-N-alkylsulfonamides by the reaction of N-toluenesulfonyl aziridines with trifluoromethyl hypofluorite, according to the equation: ##STR4## wherein R.sup.1 is CH.sub.3 and R.sup.2, R.sup.3 and R.sup.4 are H or CH.sub.3.
Grakauskas and Baum, J. Org. Chem., 35, 1545 (1970) describe the preparation of N-fluoro-N-alkylcarboxamides by reaction of the N-alkylcarboxamide with fluorine/nitrogen mixtures at 0.degree.-5.degree. C., according to the equation: ##STR5## wherein R and R' are alkyl or substituted alkyl. No utility for the products is disclosed.
Grakauskas and Baum, J. Org. Chem., 34, 2840 (1969) describe the preparation of N-fluoro-N-substituted carbamates by reaction of a carbamate with fluorine/nitrogen mixtures at 0.degree. to -20.degree. C., according to the equation: ##STR6## wherein R and R' are alkyl, substituted alkyl, or cycloalkyl. The products may be further converted to difluoroamino compounds.
The fluorination of carbanions by N-fluoro-N-alkylsulfonamides does not appear to be disclosed in the art. Fluorinations have been reported using N-fluoroperfluoropiperidine (FPFP), perchloryl fluoride or 1-fluoro-2-pyridone.
Banks and Williamson, Chem. Ind., 1864 (1964) disclose the fluorination of sodium 2-nitropropanide (40% yield) and of sodium diethyl malonate (5% yield) by reaction with FPFP, according to the respective equations: ##STR7##
Polishchuk and German, Tet. Lett., 5169 (1972) disclose the fluorination of sodium phenolate according to the equation: ##STR8##
The use of perchloryl fluoride as a fluorinating agent for anions is reviewed by Sheppard and Sharts, Org. React., 21, 225 (1974). Some typical examples include: ##STR9##
Purrington and Jones, J. Org. Chem., 48, 761 (1983) disclose that 1-fluoro-2-pyridone fluorinates malonate anions, but in variable low yields, according to the equation: ##STR10##